The present invention relates to dispensing stations for chemicals and the like. More particularly, it relates to methods and apparatus for providing a clean air working environment for operators who utilize or transfer chemicals and the like.
There is a great need to provide protection for these operators. Often, they work in local areas, known as dispensing or work stations, and care must be taken to keep the chemicals or other materials from airborne dispersion beyond the stations. Additionally, the operator must be protected from airborne dispersion of the material he or she is working with. For example, within the dispensing station there may be containers of chemicals and the like which are mixed with other chemicals, transferred to other containers, or loaded for transport. The mixing, transfer, weighing and/or loading operations, whether carried out manually or automatically, will create airborne particles against which the operator in the local station and other individuals in the environment must be protected.
One method of attempting to ensure operator safety is the use of contained suits, which provide their own breathing supply and apparatus. This provides local protection for the operator-he or she is totally isolated from the external environment. The use of these suits is cumbersome, however, and they are operator dependant, that is, the material cannot be manipulated, or in some cases the room where the transfer is occurring even entered, without a suit. Additionally, the material, whether chemical or other material, may simply not require the degree of protection that a contained suit provides. Thus, the use of a room planned around contained suit handling of materials may be unduly cumbersome for some materials.
Another alternative is the use of forced air circulating through the ceiling of the room in which the stations are located. This practice, often known as downflow, provides generalized protection to the room as whole. It lessens the chance of the room air below carrying airborne particles by developing an air pattern that directs the air toward exhaust panels.
This sort of generalized airflow, however, provides less than optimum protection. It fails to protect against local eddies or other local zones of recirculation that often carry airborne particles and occur within a dispensing station because of obstructions such as the operator's head and body or other causes such as operator movement. The local zones--with their attendant particle concentrations are especially of concern if they occur in the operator's breathing area, such as when the operator stands near the container or bends over the container when scooping materials from the container.
Therefore, it is an object of the present invention to provide methods and apparatus for the provision of local comfort zones in a dispensing station environment.